Short-range test of the universality of gravitational constant G at the millimeter scale using a digital image sensor. (23rd August 2017) - Ninomiya, K
Abstract: The composition dependence of gravitational constant G is measured at the millimeter scale to test the weak equivalence principle, which may be violated at short range through new Yukawa interactions such as the dilaton exchange force. A torsion balance on a turning table with two identical tungsten targets surrounded by two different attractor materials (copper and aluminum) is used to measure gravitational torque by means of digital measurements of a position sensor. Values of the ratios G ~ A l − W / G ~ C u − W − 1 and G ~ C u − W / G N − 1 were ( 0.9 ± 1.1 s t a ± 4.8 s y s ) × 10 − 2 and ( 0.2 ± 0.9 s t a ± 2.1 s y s ) × 10 − 2, respectively; these were obtained at a center to center separation of 1.7 cm and surface to surface separation of 4.5 mm between target and attractor, which is consistent with the universality of G . A weak equivalence principle (WEP) violation parameter of η A l − C u ( r ∼ 1 c m ) = ( 0.9 ± 1.1 s t a ± 4.9 s y s ) × 10 − 2 at the shortest range of around 1 cm was also obtained.